Make non-constexpr span helper methods inline.

Change-Id: I3188caeaf57c25cfb9f35913f42b4ebba353b42c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5018554
Commit-Queue: danakj <danakj@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Auto-Submit: danakj <danakj@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1223137}

base/containers/span.h

@@ -488,15 +488,16 @@ span(Container&&) -> span<T, X>;
 
 // [span.objectrep], views of object representation
 template <typename T, size_t X>
-span<const uint8_t, (X == dynamic_extent ? dynamic_extent : sizeof(T) * X)>
+inline span<const uint8_t,
+           (X == dynamic_extent ? dynamic_extent : sizeof(T) * X)>
 as_bytes(span<T, X> s) noexcept {
   return {reinterpret_cast<const uint8_t*>(s.data()), s.size_bytes()};
 }
 
 template <typename T,
           size_t X,
           typename = std::enable_if_t<!std::is_const_v<T>>>
-span<uint8_t, (X == dynamic_extent ? dynamic_extent : sizeof(T) * X)>
+inline span<uint8_t, (X == dynamic_extent ? dynamic_extent : sizeof(T) * X)>
 as_writable_bytes(span<T, X> s) noexcept {
   return {reinterpret_cast<uint8_t*>(s.data()), s.size_bytes()};
 }